The invention relates to a rolling mill drive with drive spindles, which are arranged between drive units and driven rolls and which terminate in spindle heads. One spindle head in each case is connected detachably to the neck of a roll, in particular of a working roll. A coupling and decoupling device is arranged between the neck of the roll and the spindle head of the drive spindle.
The working rolls used in roll stands are driven by electric motors either directly or via supporting or intermediate rolls. The transmission of the drive torque to the height-adjustable rolls takes place via drive spindles in order to compensate for the angular displacements caused by different rolling strip thicknesses. The drive spindles can be formed by articulated shafts or toothed spindles and make length compensation possible in the axial direction. Pinion gearings or twin drive gearings are usually additionally interposed between the drive motors and the drive spindles. During day-to-day rolling operation, the working rolls are subjected to great mechanical stresses and, on account of constant rolling program change, they also have to be exchanged frequently. This requires a coupling and decoupling device appropriate to these great stresses between the neck of the driven roll and the drive spindle transmitting the drive torque. A number of such releasable connecting elements are already known but do not adequately meet the requirements with regard to mechanical loadability and short coupling and decoupling times with high operational reliability and a low maintenance requirement.
A possible embodiment of a coupling and decoupling device used on rolling mill drives is a ring bayonet closure such as is illustrated and described in EP-B 0 324 978 or DE-A 40 35 941. In both cases, the bayonet closure consists of a closure pin and an externally toothed closure wheel which can be rotated relative to the closure pin and can be positioned in such a way in relation to the closure pin by an adjusting device likewise comprising a toothing that the teeth on the closure pin and on the closure wheel which lie opposite one another in an operating position are staggered in a release position and separation of the components is thus possible. The high production outlay for the toothings and the exacting requirements for the production tolerances of all the components are disadvantages of these constructions. Furthermore, very accurate positioning of the driven working roll, the drive spindle and the spindle mounting in relation to one another is necessary in order to ensure distortion-free interaction of the components. On the other hand, the production tolerances necessary on the heavy components can lead to jamming of the bayonet during mounting work.
A locking device for a releasable connection between a drive spindle and a roll neck in a rolling mill is likewise already known from DE-C 44 10 306 and DE-A 195 08 526. In this case, when the shaft journal is introduced into a coupling sleeve, a spring-loaded locking bar engages automatically in a recess of the shaft journal and forms a play-free connection. The locking bar engages in this recess at an angle of 45° to 55° to the shaft axis and makes the opposed decoupling operation possible when a movement counter to the coupling direction takes place along inclined guide surfaces. A radially displaceable securing bolt, which is held in a locking position under spring loading, prevents automatic decoupling of the connection. The securing bolt can be displaced into release position by intervention from outside, for which a separate opening tool is necessary, after which the pulling-off movement of the driven rolls initiates separation from the articulated shaft. A major disadvantage of this solution is that two locking devices offset by 180° in relation to one another have to be arranged in order to avoid unbalance in the drive system, or special balancing is necessary. In addition, this solution consists of many individual parts and therefore involves high production outlay.
Releasable couplings with radially displaceable locking bolts for positionally fixed connection of a sleeve on a shaft are known from U.S. Pat. No. 4,392,759 and U.S. Pat. No. 3,926,532 for example. According to U.S. Pat. No. 4,392,759, locking bolts arranged radially in a sleeve engage counter to spring force in an annular groove of a splined shaft and in this way secure the connection between shaft and sleeve. The locking bolts are held in this locking position by a locking sleeve which is displaceable axially counter to a spring force. As this is a simple manually operated device with a rotating/sliding sleeve for comparatively small loads, this device is not suitable for problem-free use in rolling mills. Furthermore, adequate security against unintentional opening is lacking. An embodiment of a coupling which is largely similar is disclosed in U.S. Pat. No. 3,926,532, in which the locking sleeve can be brought into a release position by a rotary movement in the peripheral direction counter to spring force.